TY - JOUR

T1 - Vulnerability of Temperate Mesophotic Ecosystems (TMEs) to environmental impacts: Rapid ecosystem changes at Lough Hyne Marine Nature Reserve, Ireland

AU - Micaroni, Valerio

AU - McAllen, Rob

AU - Turner, John

AU - Strano, Francesca

AU - Morrow, Christine

AU - Picton, Bernard

AU - Harman, Luke

AU - Bell, Jame J.

PY - 2021/10/1

Y1 - 2021/10/1

N2 - AbstractTemperate Mesophotic Ecosystems (TMEs) are stable habitats, usually dominated by slow-growing, long-lived sessile invertebrates and sciaphilous algae. Organisms inhabiting TMEs can form complex three-dimensional structures and support many commercially important species. However, TMEs have been poorly studied, with little known about their vulnerability to environmental impacts. Lough Hyne Marine Nature Reserve (Ireland) supports TMEs in shallower waters (12–40 m) compared with other locations (30–150+ m) as a result of the unusual hydrodynamic conditions. Here, we report changes that have occurred on the sponge-dominated cliffs at Lough Hyne between 1990 and 2019, providing insights into TME long-term stability and vulnerability to environmental impacts. Our main finding was a marked decline in most three-dimensional sponges at the internal sites of the lough. This was likely the result of one or more mass mortality events that occurred between 2010 and 2015. We also found an increase in ascidians, which might have been more tolerant and benefited from the space freed by the sponge mortality. Finally, in the most recent surveys, we found a high abundance of sponge recruits, indicating that a natural recovery may be underway. The possible factors involved in these community changes include eutrophication, increased temperature, and a toxic event due to an anomaly in the oxycline breakdown. However, the absence of comprehensive monitoring of biotic and abiotic variables makes it impossible to identify the cause with certainty. Our Lough Hyne example shows the potential vulnerability of TMEs to short-term disturbance events, highlighting the importance of monitoring these habitats globally to ensure they are appropriately conserved.

AB - AbstractTemperate Mesophotic Ecosystems (TMEs) are stable habitats, usually dominated by slow-growing, long-lived sessile invertebrates and sciaphilous algae. Organisms inhabiting TMEs can form complex three-dimensional structures and support many commercially important species. However, TMEs have been poorly studied, with little known about their vulnerability to environmental impacts. Lough Hyne Marine Nature Reserve (Ireland) supports TMEs in shallower waters (12–40 m) compared with other locations (30–150+ m) as a result of the unusual hydrodynamic conditions. Here, we report changes that have occurred on the sponge-dominated cliffs at Lough Hyne between 1990 and 2019, providing insights into TME long-term stability and vulnerability to environmental impacts. Our main finding was a marked decline in most three-dimensional sponges at the internal sites of the lough. This was likely the result of one or more mass mortality events that occurred between 2010 and 2015. We also found an increase in ascidians, which might have been more tolerant and benefited from the space freed by the sponge mortality. Finally, in the most recent surveys, we found a high abundance of sponge recruits, indicating that a natural recovery may be underway. The possible factors involved in these community changes include eutrophication, increased temperature, and a toxic event due to an anomaly in the oxycline breakdown. However, the absence of comprehensive monitoring of biotic and abiotic variables makes it impossible to identify the cause with certainty. Our Lough Hyne example shows the potential vulnerability of TMEs to short-term disturbance events, highlighting the importance of monitoring these habitats globally to ensure they are appropriately conserved.

KW - Temperate mesophotic ecosystems, Monitoring SpongesBenthic communities. Mass mortality, Circalittoral

U2 - 10.1016/j.scitotenv.2021.147708

DO - 10.1016/j.scitotenv.2021.147708

M3 - Article

VL - 789

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

M1 - 147708

ER -